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TP: Cheap secondary wireless flash?

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georgiaboy View Drop Down
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Post Options Post Options   Quote georgiaboy Quote  Post ReplyReply Direct Link To This Post Posted: 17 March 2007 at 22:28
Originally posted by Alain Alain wrote:





Hi I'm sceptical about ignoring preflashes, I have a very cheap "digital" slave flash with 5 options, but none of them works.
I would be very happy to know if a specific type is working...

I did post the question also to sebi, he has made an convertor board for older flashes.

Alain


Hi again Alian. I'm also very interested in any circuit that would work. Please let me know. The configeration I described at the beginning of this thread is working for me right now, But, like chych I would like to use my EF 500 DG as the main in wireless mode. The Sunpak 433, Vivitar 283/5, or any multi auto thryistor with multi selectable output is what I want to control optically. It will probably be three weeks before this Chinese version arrives.
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Alain View Drop Down
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Post Options Post Options   Quote Alain Quote  Post ReplyReply Direct Link To This Post Posted: 18 March 2007 at 00:26
Hi

Some good news, I was reading the timings on the mhohner flashcompendium and I noticed that the 7D only gives 1 preflash when an external flash is on camera.

I tested it with my 5D and 5600hs and a cheap digital slave flash and it's working: only one preflash, this is ok for almost all "digital" slaves.

Then I went looking at the internet and there are links to some DIY digital slaves, the first has used / is using an km 7D and has sent it for testing to Pete Ganzel! :

Rolf's Slave trigger

I have the impression that he has pcb made, but it's uncertain for me... Will he sell them as a unit???

Another nice one :

other smart slave trigger

and there are others...

Alain
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MojoRick View Drop Down
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Post Options Post Options   Quote MojoRick Quote  Post ReplyReply Direct Link To This Post Posted: 18 March 2007 at 01:30
I e-mailed Rolf asking if he is selling the PCB and programed PIC. We e-mailed each other several times when he was developing it last September. My how time flies!

Originally posted by Alain Alain wrote:

Hi

Some good news, I was reading the timings on the mhohner flashcompendium and I noticed that the 7D only gives 1 preflash when an external flash is on camera.

I tested it with my 5D and 5600hs and a cheap digital slave flash and it's working: only one preflash, this is ok for almost all "digital" slaves.

Then I went looking at the internet and there are links to some DIY digital slaves, the first has used / is using an km 7D and has sent it for testing to Pete Ganzel! :

Rolf's Slave trigger

I have the impression that he has pcb made, but it's uncertain for me... Will he sell them as a unit???

Another nice one :

other smart slave trigger

and there are others...

Alain
Rick
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sooten View Drop Down
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Post Options Post Options   Quote sooten Quote  Post ReplyReply Direct Link To This Post Posted: 18 March 2007 at 02:33
Hey guys, I went to the local camera shop on Friday and played with one of those digital peanuts from Wein plugged into a Vivtar 285. It worked right everytime with both the pop-up and the 56 on camera. I forgot to try it with the two in wireless mode, so I will make another trip on Monday.

The way we tested to make sure of the actual firing was by pointing the slave equipped flash directly into the camera. In that way we could be sure it was firing at the proper time.

I will let you all know what I find out at the shop on Monday.

Scott
Scott
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chych View Drop Down
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Post Options Post Options   Quote chych Quote  Post ReplyReply Direct Link To This Post Posted: 18 March 2007 at 03:10
sooten, make sure you take actual pictures with the slave flash. Even if it appears to be firing correctly, it may still not be synchronized with the shutter (try and have an obvious arrangement to see if the slave flash is making it into the image, i.e. point the flash into the camera lens).

Regarding the circuits, I like the idea of DIY and building a solution. However I do not like the idea of using a computer to do this (the PIC), since it is a pain to program a PIC (you need the right tools to do this). I suspect one could make something that would work using a photo-transistor, some capacitors and logic gates to ignore the pre-flash, which would make it PIC-free. I sketched a quick circuit up, maybe I'll try it some time (though since I'm not an electrical engineer, I'm not sure this will work!).
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Post Options Post Options   Quote MojoRick Quote  Post ReplyReply Direct Link To This Post Posted: 18 March 2007 at 03:12
They are kind of tricky to test for proper operation. I just now tested my Sunpak 120J with the WolfCamera/Ritz generic opto-slave trigger. Note: I have the KM 5D which is the same flash-wise as the A100. The KM 7D has true manual flash with no pre-flash mode.

If I set the Sunpak to less than full strobe, it will recharge fast enough to do both the pre-flash and the main flash. When I use the Sunpak external battery pack TR-PAKII it does a little better to recharge in time. If one could figure out how to make the camera set a longer period between pre-flash and main flash, it would work all the time, and for all power levels.

So, if your flash cannot recharge super quickly, you are back to Manual mode on the 5D and 5600 in order to only get a main flash.

Note: the on board flash on the 5D cannot be set to manual mode and so will not work.

The bottom line is that if you can see the slave fire in the viewfinder, then it responded to the pre-flash. If it can re-charge before the main flash it will fire then also. My 120J is very quick on the re-draw and has a big cap, therefore it will trick you into thinking the opto-slave works. lol



Originally posted by sooten sooten wrote:

Hey guys, I went to the local camera shop on Friday and played with one of those digital peanuts from Wein plugged into a Vivtar 285. It worked right everytime with both the pop-up and the 56 on camera. I forgot to try it with the two in wireless mode, so I will make another trip on Monday.

The way we tested to make sure of the actual firing was by pointing the slave equipped flash directly into the camera. In that way we could be sure it was firing at the proper time.

I will let you all know what I find out at the shop on Monday.

Scott
Rick
 



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MojoRick View Drop Down
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Post Options Post Options   Quote MojoRick Quote  Post ReplyReply Direct Link To This Post Posted: 18 March 2007 at 03:16
BTW, I ordered one of Rolf's PIC solutions. I will give a review when it comes in. He is an interesting fellow. I wish he was on this forum.
Rick
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Post Options Post Options   Quote chych Quote  Post ReplyReply Direct Link To This Post Posted: 18 March 2007 at 05:22
Well if anyone is interested, I'm looking to create a simple optical trigger that does not require a PIC (thus anyone can build it without getting a PIC programmer and writing code). Seeing that I'm a mechanical engineer with some limited electronics knowledge, anyone care to look over this design I've been sketching? I haven't bothered to determine what the resistors/capacitor values should be, but I'm wondering if my logic/layout is correct. Anyways, total cost of components should be <$5.

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Post Options Post Options   Quote MojoRick Quote  Post ReplyReply Direct Link To This Post Posted: 18 March 2007 at 05:39
Very well thought out.

A reset to a known condition is needed. What if the camera flashes an AF signal?
Rick
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Post Options Post Options   Quote chych Quote  Post ReplyReply Direct Link To This Post Posted: 18 March 2007 at 05:59
Ooh those AF assist signals would be rather annoying. If a big flash is on and it uses its AF assist red lamp, then it won't be a problem. A cheap laser pointer with a hologram attachment can be used for AF assist as well, and this works much better than the built-in flash AF assist.

I just tried this with my EF-500 in slave mode, it appears that the AF assist flash is weaker than the preflash. Then R1 can be tweaked to trigger only on preflash.

I designed it so that whenever C1 hits TTL high as it charges, it flips the T flip flop, which disables the C1 charger, enables T2 that discharges C1, and goes into 'low' mode, so the system always wants to go to this 'low' condition.

Edited by chych - 18 March 2007 at 06:00
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Post Options Post Options   Quote Alain Quote  Post ReplyReply Direct Link To This Post Posted: 18 March 2007 at 11:08

Just another DIY one, but this has the possibility to wait. Looking at some of the diagrams in the flash compendium and Friedman page (links on dyxum flash section) I see that the main flash is after about ~140ms and the wireless system gives preflashes for about the first 105ms.

So on first flash start ignoring for 110-120 ms (adjustable off course) and then waiting for the flash.

I think this diagram does just that :

slave flash trigger
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Alain View Drop Down
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Post Options Post Options   Quote Alain Quote  Post ReplyReply Direct Link To This Post Posted: 18 March 2007 at 11:09
Originally posted by MojoRick MojoRick wrote:

BTW, I ordered one of Rolf's PIC solutions. I will give a review when it comes in. He is an interesting fellow. I wish he was on this forum.


I'm looking forward to it.

Alain
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georgiaboy View Drop Down
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Post Options Post Options   Quote georgiaboy Quote  Post ReplyReply Direct Link To This Post Posted: 18 March 2007 at 11:19
Originally posted by sooten sooten wrote:

Hey guys, I went to the local camera shop on Friday and played with one of those digital peanuts from Wein plugged into a Vivtar 285. It worked right everytime with both the pop-up and the 56 on camera. I forgot to try it with the two in wireless mode, so I will make another trip on Monday.

The way we tested to make sure of the actual firing was by pointing the slave equipped flash directly into the camera. In that way we could be sure it was firing at the proper time.

I will let you all know what I find out at the shop on Monday.

Scott


These, as mentioned before, are available from B&H for 79.00 for a three pack. I have read several bad reviews however. They are very small and durable, Please report back as soon as you can. They , if work properly, will make a great solution.
"I'm fixing a hole where the rain gets in..."
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Post Options Post Options   Quote sooten Quote  Post ReplyReply Direct Link To This Post Posted: 18 March 2007 at 18:45
Originally posted by chych chych wrote:

sooten, make sure you take actual pictures with the slave flash. Even if it appears to be firing correctly, it may still not be synchronized with the shutter (try and have an obvious arrangement to see if the slave flash is making it into the image, i.e. point the flash into the camera lens).



Chych, this is exactly what I did. The guy at the shop pointed the flash directly into the camera lens. We took about 10 pics, and in every one, the flash was blowing out the picture. I will post the pics of our test Monday after we do it.
Scott
He who laughs last thinks slowest!
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